1. Field of the Invention
The invention concerns a device for sorting raw, pre-treated or recycled bulk materials, which are comprised of individual components to be sorted, wherein the classification of the parts to be sorted occurs along empirically determined classification parameters and the material which is sorted is removed, the device having a conveyance device for supplying the bulk material, a conditioning device for wetting the bulk material, a break-down device for breaking down the bulk material into individual parts to be sorted, a sensor device for sensing the classification-relevant characteristics of the components to be sorted and for production of measurement data, which includes at least one camera, which is connected to a device for evaluation of electronically measured values with at least one micro computer for classification of the components to be sorted and for achievement of a control signal by means of a control unit, wherein the camera is associated with at least one even diffused light emitting light source.
2. Description of the Related Art
A device for sorting bulk materials is known from EP 0 562 506 A2. This includes an optical sensor head, which is associated with an illumination device with white light. The signals obtained by the sensor head during passage-by of individual glass fragments are transmitted to a computer and a control unit, which controls a compressed air jet. A stream of compressed air can remove an undesired glass fragment. This known device has the disadvantage, that the glasses to be sorted must be individualized and the recognition of materials to be selected for removal is only imprecisely possible. The sorting thus occurs rather slowly and imprecisely.
From DE 295 13 718 U it is also known, to select as the light source one which emits an even diffuse light, wherein also multiple light sources can be employed. Thereby the individual bulk materials are illuminated without shadows, so that they can be sensed by the at least one camera without interference. In the case of, for example, mineral bulk materials, including those which are abrasive, there is the disadvantage, that by the development of dust the light sources are soiled, so that the illumination of the bulk material required for the camera or, as the case may be, cameras, is diminished, which can result in erroneous measurement.
With the known devices there is further the problem, for objects which are smaller than 5 mm, of a poor reliability of illumination which is related to varying conveyance speeds. A mistake at the beginning of the slide, via which the bulk material is supplied to the sensor device, is amplified as the height of falling is increased. Due to the normally large fractions the geometric dimensions of the sensor device and device for compressed air jets cannot be easily reduced to a size as small as desired, it has been attempted to harmonize the speed of the objects. Attempts with a slitted rubber curtain in the area of the discharge edge on which the downwardly directed slide is provided resulted in no satisfactory results. It has thus also been proposed, to provide at the inlet of the slide a cell wheel or gate wheel which can be constructed for example as a bristle roller. With small object this does not however produce the desired degree of control.
The task of the invention is concerned with improving the device of the above described type in such a manner that as well with bulk materials as with small objects a good degree of positive feed control is achieved with appropriately matched or harmonized fall rates of the objects and that a soiling of the light sources is prevented or, as the case may be, can be eliminated in a simple manner, without requiring a lengthy interruption of the operation of the device.
The solution of the problem is inventively solved in accordance with the present invention as discussed below.
The sorting of raw, pre-treated or recycled bulk material with the inventive device is based upon an opto-electronic recognition system. This system analyzes and evaluates these objects. The results are then transmitted to a control electronic. This control electronic controls individual components of the modularly designed separation device, in order to deflect the individual objects from the bulk material stream. The bulk material stream is delivered by a conveyor to the device and fed to a unit for breaking down and individualizing. From this breaking down and individualizing unit the bulk material stream is conveyed in a direction of the separation device, wherein the bulk material items can be conveyed in troughs, grooves, ridges, tracks, or chaotically. The bulk material stream is brought into a free fall. As soon as the free fall occurs, the bulk material stream is scanned with the aid of a cell and/or matrix camera. Each object is then evaluated by the evaluation electronic and removed from the separation device or as the case may be from the bulk material stream. Thereby a separation of the objects of the bulk material into a reject path and an approved path is possible. The evaluation electronic can be provided on the basis of a micro computer and/or by DSP, RISC, CISC and makes possible hierarchical and/or parallel data processing.
The evaluation of the individual objects of the bulk material stream results from the detection of the lightness of the material surface via the reflection behavior or response. In transparent materials occlusions can be detected. It is possible to detect the shape of the objects of the bulk material. Thereby the center of gravity of the individual objects can be determined, which facilitates the appropriate controlling of the components of the separation device for the separating out of objects to be sorted out. A determination of size can also be undertaken by a conditioning device, which is to be provided prior to the break-down and individualizing device. By means of an appropriate CCD-sensor of the cell and/or matrix camera it is also possible to have a pixel-individual evaluation, whereby the recognition of the color texture of the object of the bulk material can be improved. The color recognition can be black and white or be accomplished in 256 steps of grayness by utilization of a black/white camera system. With such a camera system semi-real colors can also be determined by the employment of filters. With utilization of a color camera system real colors will be detected. It is also possible to increase the throughput of the bulk material stream thereby, that multiple observation planes are provided sequentially.